1. Field of the Invention
The present invention relates to a radio communication terminal having a non-contact communication function of making radio communication using an induced magnetic field between a non-contact IC card reader/writer device (hereinafter referred to as reader/writer) by being placed in the inductive magnetic field radiated from an antenna of the reader/writer. The present invention relates to, for example, a portable phone having a non-contact IC card function used by holding it up to the antenna of the reader/writer at an automatic ticket gate installed at a ticket gate in a railroad station.
The present invention relates to a radio communication terminal housing case for housing such a radio communication terminal. The present invention relates to a radio communication terminal sheet capable of being mounted on the radio communication terminal. The present invention relates to a radio communication terminal display device capable of being mounted on the radio communication terminal.
2. Description of the Related Art
As a conventional non-contact IC card (hereinafter referred to as IC card), one which is used at the automatic ticket gate installed at the ticket gate in the railroad station is known for example. This IC card has an integrated circuit (IC) for processing a plurality of calculations and controls and has a resonant circuit for making non-contact communication with an external device, and the resonant circuit is sometimes composed of a loop coil, a capacitor and a resin material covering the IC. Such an IC card sometimes has the resonant circuit having no capacitor.
The loop coil, the capacitor and a capacitor component parasitic on or set to the connecting part of the IC compose the resonant circuit resonating with the induced magnetic field radiated from the antenna of the reader/writer on the automatic ticket gate side. This conventional IC card utilizes a voltage induced by the resonant circuit to generate operation power for the IC from a power supply circuit of a rectifying circuit, etc., of the IC and performs communication, control and data writing and reading to and from a memory.
In recent years, a variety of radio communication terminals such as a portable phone with a function owned by this type of IC card incorporated therein have been come into existence. This radio communication terminal is very small in size. Therefore, it cannot mount a loop coil with a size larger than the loop area to obtain the operation power necessary for the IC card. Accordingly, most of the IC cards are structured in which the operation power for an IC (hereinafter referred to as non-contact IC) incorporated in the communication terminal to have a function equivalent to that of the IC card and is supplied form a battery of the communication terminal and a small size of a loop coil is employed for use in communication. Since the communication terminal has electronic components and the battery to achieve a variety of terminal functions thereinside other than a communication function (phone function), it has a metal member (radio wave shielding object) to prevent the influence (noise, etc.) of the communication function onto the incorporated electronic components. Then, the communication terminal is miniaturized as mentioned above, so that there is the metal member close to or back face of the mounted loop coil for the housing of inner components in the communication terminal.
Therefore, the magnetic field radiated from the loop coil generates an eddy current on the surface of the metal member to suppress the magnetic field, so that the density of the magnetic field becomes weak as a result. To solve such a problem, a technique to make the loop coil movable and to form a gap between the loop coil and the metal member is disclosed in Jpn. Pat. Appln. KOKAI Publication No. 2003-330898.
However, other problems such that a trouble to be required to purposely move the loop coil at communication, a movable section is damaged, the cost of the communication terminal equipment is increased on ground of the mounting of the movable section, etc.
There is a method for improving the magnetic field intensity on a loop coil front face by inserting a ferrite material, etc., between the loop coil and a metal plate and securing high magnetic permeability while suppressing a magnetic loss so as to reduce the influence of the eddy current on the back face of the loop coil. Although the magnetic field intensity on the front face of the loop coil can be improved by this method, it is impossible to generate a similar magnetic field at the rear of the metal plate disposed on the back face of the loop coil.
Meanwhile, the communication though the IC card is one to demodulate variations of the introduced magnetic field radiated from the reader/writer to receive data and one in a load switching system to reply the data to the reader/writer by switching the loop coil receiving the induced magnetic field radiated from the reader/writer to vary a space impedance with the induced magnetic field related thereto and by utilizing a part of energy of the induced magnetic field.
Consequently, in the case that the front face of the loop coil mounted on the radio communication terminal is held up so as to face the antenna, the loop coil can generate an extremely strong induced power compared to the case that the back face of the loop coil is held up so as to face the antenna. As a result, this large difference in induced power comes out as a difference in a communication distance between front face holding up and back face holding up.
Therefore, the portable phone prints a mark on a housing side with the loop coil mounted thereon and displays a face to be held up toward the reader/writer. However, in the case that the portable phone is used at the automatic ticket gate installed at the ticket gate in the railroad station, wrong faces are frequently held up because passengers are in hurry, and such problems of occurrence of passage interference such as frequent closing of the ticket gate and the problem of incomplete processing such as entrance with a portable phone which is in a state of processing incompletion occur.